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Additional Biology

GCSE AQA B2
by

leighanna Teal Dawson

on 12 May 2015

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Transcript of Additional Biology

Temperature and pH
Changing the temperature changes the rate of an enzyme-catalysed reaction. like with any reaction, high temperature increases the rate at first. but if it gets too hot, some of the bonds holding the enzyme together bareak. this destroys the enzyme's special shape and so it wont work any more. It is said to be denatured. All enzymes in the human body need to be 37ᵒc. Also enzymes need to be at a good pH for their job.If the pH is too high or too low the enzyme will be denatured. all enzymes havw an optimum pH, e.g. in the stomach pH 2 is needed.
Specialised shapes
What are enzymes?
Cells
Enzymes
Plants
Additional Biology
Enzymes are catalysts produced by living things. living things have thousands of different chemical reactions going on all this time. these reactions need to be carefully controlled. you can usually make reactions happen more quickly by raising the temperature. this would usually speed up useful reactions but also the unwanted ones to, e.g. bacteria. there's also a limit to how far you can raise the temperature inside a living creature before its cells start getting damage. enzymes are all proteins and all proteins are made up of chains of amino acids. these chains are folded into unique shapes, which made enzymes the are specialised to do their specific jobs. as well as catalysts, proteins act as structural components of tissues, hormones and antibiotics.
Chemical reactions usually involve things either being split apart or joined together. Every enzyme has unique structure to suit the reactants involved. Enzymes usually only catalyse one reaction. this is because, for the enzymes to work, the substance has to fit its special shape. if the substances doesn't match the enzyme's shape, then the reaction won't be catalysed.
Enzymes and Digestion
Digestive enzymes breakdown big molecules into smaller molecules.Starch,proteins and fats are big molecules. They're too big to pass thought the walls of the digestive system. Sugars,amino acid and glycerol and fatty acids are much smaller molecules.
Amylase Converts Starch into Sugars
Amylase are made in the Salivary glands, pancreas, small intestine.
Protease Converts Proteins into Amino Acid
Protease are made in the stomach, pancreas, small intestine.
Lipase Converts Lipids into Glycerol and Fatty Acids

Lipase are made in the pancreas, small intestine
Protease Proteins → amino acids
Amylase Starch → sugars

Amylase is an example of a carbohydrate.

Lipase Lipids → fatty acids + glycerol
Lipids are fats and oils.
Enzymes in Respiration
Respiration is not breathing!
respiration is the process of releasing energy from the breakdown of glucose - and it goes on in every cell in the human body.
Aerobic Respiration
Aerobic respiration is respiration using oxygen.
Equation
Glucose+Oxygen→Carbon Dioxide+Water+Energy
Uses of Respiration
To Build up larger molecules from smaller ones like proteins from amino acids.
In animals, to allow the muscles to contract.
In mammals and birds the energy is used to keep the body temperature steady.
In plants, to build sugars , nitrates and other nutrients into amino acid, which are then build up into proteins.
Glycogen in Exercise
Some glucose from food is stored as glycogen. Glycogen's mainly stored in the liver, but each muscle also has its own store. During vigorous exercise muscles use glucose rapidly. So some of the stored glycogen is converted back to glucose to provide more energy.
Anaerobic
When you do vigorous exercise and your body can't supply enough oxygen to your muscles, they start doing anaerobic respiration instead of aerobic respiration. An aerobic means without oxygen. it's he incomplete breakdown of glucose, therefore it produces lactic acid.
Equation
Glucose→Energy +Lactic Acid
Effects of Lactic Acid
This causes muscle fatigue and stops muscle contracting efficiently. Also anaerobic respiration does not release nearly as much energy.
Anaerobic respiration leads to oxygen debt. This means you need to repay oxygen. This means you have to keep breathing hard for a while your blood is reoxygenated and and lactic acid is turned back into carbon dioxide and water.
Uses of Enzymes
Enzymes are used in biological detergents. They're mainly protein-digesting enzymes (proteases) and fat-digesting enzymes (lipases). This helps breakdown animal and plant matter such as food and blood stains.
Also enzymes are used in; baby food (to pre-digest food), slimming foods and drinks(to make food sweeter with less sugar and to turn starch syrup into sugar syrup.
Also enzymes are used in industry to speed up reactions without high temperature of pressure.
Enzymes in Industry
They are very specific so only catalyse the reactions want you want.
Using lower temperatures and pressures saves money.
Enzymes work for a very long time.
They are biodegradable (so there is less pollution).
Advantages
Some people are allergic to the enzymes.
Small increases in temperature and pH can denature them.
They can be expensive to buy.
They can also contaminate the products of the reaction.
Disadvantages
Distribution of Organisms
Fossils and Extinction
DNA
Cell Division
Stem Cells
Genetics
Bacteria Cell
Animal Cell
Fungus Cell
Plant Cell
Animal and Plant Cells
Functions
Nucleus-Contains genetic information and controls the cell.
Cytoplasm- Where chemical reactions take place.
Cell Membrane-Holds cell together and controls at goes in and out.
Mitochondria-Where most respiration happens.
Ribosomes-Where proteins are made.
Chloroplasts-Where photosynthasis occurs.
Vacuole-Cell sap-contains a solution of salts and sugars.
Cell Wall-To support and strangthen the cell.
Plasimds-DNA provides bacteria with genetic advantages, such as antibiotic resistance.

Diffusion
Diffusion is the gradual movement of particles from high to low concentration. It happens in both solids and gases, because the particles are free to move around.
The bigger the difference in concentration, the faster the diffusion rate.
Diffusion
Diffusion
Cells
Animal, plant, fungal and bacterial.
Specialised Cells
Palisade Leaf Cells
Palisade leaf cells are adapted for photosynthesis. they are packed with chloroplasts for photosynthesis. they are positioned so more of them are crammed on the top layer, so the cells get more light. Tall shaped cells mean that a lot of surface area is exposed down the sides, so more CO is absorbed. a this shape means that you can pack loads of them in at top of a leaf.
Palisade Leaf Cells
Palisade leaf cells are grouped together at the of the leaf where most of the photosynthesis happens.
Guard Cells
Guard cells are special kidney shaped cells which open and close the stomata in the leaf. When the plant has lots of water the guard cells fill with it and go turgid and plump. This makes the stomata open so gates can be exchanged for photosynthesis. when the plant is short of water the guard cell becomes flaccid making the stomata close. This prevents too much water vapour escaping. Thin outer walls and thickened inner walls making the actions work. They're also sensitive to light and close at night to save water.
Guard Cells
Guard cells are therefore a adapted to their function of allowing gas exchange and controlling water loss within a leaf.
Red Blood Cells
Red blood cells are concave in shape to provide a larger surface area for absorbing oxygen. It also helps the cells pass through capillaries with ease. along side this they are packed with haemoglobin, they also have no nucleus to provide more room for haemoglobin.
Red Blood Cells
Red blood cells are adapted by having no nucleus and concave shape.
Egg and Sperm
The main function of an egg cell is to carry the female DNA and to nourish the developing embryo in the early stages. The egg cell contains huge food reserves to feed the embryo. When a sperm fuses with the egg, the egg's membrane instantly changes its strucure to stop any more sperm getting in. This makes sure the offspring end up with the right amount of DNA.
The function of a sperm is to get the male DNA to the female DNA. it has a long tail and streamlined head to help it swim. it also has a lot of mitochondria to provide the required energy. also the sperm carried enzymes in their heads to digest through the egg cell membrane. The tail is called the flagellum.
Egg Cell
Sperm Cell
Egg and Sperm Cells
Cell Organisation
Organism
Organ System
Organ
Tissue
Cell
Organelle
Human
Circularly system
Heart
Muscle
Muscle Cell
Nucleus






Plant Structures
Rates of Photosynthesis
Photosynthesis
How Plant Cells are Organised
Like animals plants are also made of organs, like stems,roots and leaves. these organs are made of tissues. For example, leaves are made of:
Mesophyll tissue-this is where most of the photosynthesis occurs.
Xylem and phloem-they transport things like water,mineral ions and sucrose around the plant.
Epidermal tissue-this covers the whole plant.
Photosynthesis
Photosynthesis is the process that produces 'food' in plants and algae. the 'food' it produces is glucose. it takes place in the chloroplasts, a green substance which absorbs sunlight and uses its energy to convert carbon dioxide a water into glucose. oxygen is its by-produce. Photosynthesis happens in the leaves of all green plants.
Light Intensity
Concentration of Carbon Dioxide
Temperature
At the end of photosynthesis the plant makes a sugar called glucose. Glucose is a small sugar that is soluble so can dissolve because it can be dissolved it can be transported around the plant . Glucose is reacted together to make a large sugar called starch. Starch is insoluble so it can not dissolve because it cannot dissolve it is easily stored in a particular place.

Glucose
How Plants Use Glucose
Respiration
Making Cell Walls
Making Proteins
Stored in Seeds
Stored as Starch
Plants manufacture glucose in their leaves. They then use some of the glucose for respiration. This releases energy which enables them to convert the rest of the glucose into various other useful substances, which they can use to build new cells and grow. to produce some of these substances they also need to gather a few minerals form the soil.
Glucose in coveted into cellulose for making strong cell walls, especially in a rapid growing plant.
Glucose is combined the nitrate ions (from the soil) to make amino acids, which are then made into proteins.
Glucose is turn into lipids for storing inn seeds. Sunflower seeds, for example, contain a lot of oil- we get cooking oil and margarine form them. Seeds also store starch.
Glucose is turned into starch and stored in roots, stems and leaves, ready for use when photosynthesis isn't happening, like i the winter. Starch is in soluble which makes it much better for storing than glucose a cell with lots of glucose in would draw in lots of water and swell up. Potato and parsnip plants store lots of starch underground over the winter so a new plant can grow from it following spring.
The Environment
Varies
A habitat of an organism plays a huge part in what it requires. Environmental factors such as, temperature, water availability, Carbon dioxide availability, nutrient availability and light availability.
An organism might be more common in one area than another due to differences in environmental factors between the two areas. For example, in a field, you might find that daisies are more common in the open, than under trees, because there is more light and nutrients.
Examples
Quadrants
Quadrat is usually a square made of wire. It may contain further wires to mark off smaller areas inside, such as 5 x 5 or 10 x 10 squares. The organisms underneath, usually plants, can be identified and counted.



When using a quadrat:
It should be placed randomly so that a representative sample is taken
The validity and reproducibility of the results increases as the results from more quadrats are analysed

Quadrats may also be used for slow-moving animals such as slug and snails.
Using a Quadrat
Biology
Cells
-Cells and simple cell transport
Tissues, organs and organ systems
-Organs in animals, Organs in plants
Photosynthesis
-Photosynthesis
Organisms and their environment
-Distribution of organisms
Proteins - their functions and uses
-Proteins and enzymes
Respiration
-Aerobic and anaerobic respiration
Cell division and inheritance
-DNA and cell division, Genetic variation and genetic disorders
Speciation
-Old and new species

Mitosis
Mitosis is the division of body cells.
Meiosis
Used to create sex cells.
Mitosis and Meiosis
Anaerobic and Aerobic Respiration
Exercise
Glucose-Energy+Lactic Acid
Exercise
Exercise increase heart rate. Exercise causes more muscle contractions to happen, this meant the mucles use more oxygen which can cause oxygen debt when doing vigorous exercise. this increases the rate of respiration. This respiration is called anaerobic.
Deoxyribonucleic Acid
A gene is a section od DNA. It contains instructions ti make a spacific protien. Cells make protiens by stringingamino acids together in a particular order. Amino acids are proteins and make up haemogloibin and keratin.
DNA is Unique
Only clones and identical twins have the name DNA. Forensic science can use DNA scanning to to check crime scenes. Also paternity testing using DNA testing. Data can be misinterperated.
You know that differentiation is the process by which a cell changes to become specialised for its job. In most animal’s cell, the ability to differentiate is lost at an early stage, but lots of plant cell don’t ever lose this ability. Some cells are undifferentiated. They are called stem cells. They are found embryos in early stages. They are also found in adult’s bone marrow. They could also be used to make people organs. They may one day be used to replace old cells and help those with heart diseases, diabetes, spinal injuries and damaged nerve cells.
There are 22 matcher pairs of chromosomes in every human body cell. The 23rd pair are labelled XX or XY. They’re the two chromosomes that decide whether you turn out male or female. Men have an X and Y while females have two X’s. The sperm decide this factor and it is always a 50% chance.
Embryo Screening
For
• It will help to stop people suffering.
• There are laws to stop it going too far. Currently people cannot select the sex unless it is for health reasons.
• During IVF, most of the embryos are destroyed anyway- screening just allows the selected one to be healthy.
• Treating disorders cost the government.
Against
• People may one day be able to pick to pick characteristics about their babies.
• Rejected embryos are destroyed.
• It implies people with genetic problems are undesirable.
• Scanning is expensive.

Homozygos is two of the same allelels.
Hetroztgos is different alleles.
Fossils
Fossils are the remains of organisms from many years ago, which are found in rocks.
The gradual replacement of minerals is achieved by things like teeth, shells and bones baking down. These objects are made of minerals which eventually are put back in to the ground when they decay.
Sometimes, fossils are formed when an organism is buried in a soft mineral like clay, the clay layer hardens around it and the organism decays, leaving a cast of itself. They create footprint like impressions in the rock.
Casts
Minerals
When decay cannot happen
In some stone and tar pits there is no oxygen so microbes that would allow the the dead animal to decay. also in glaciers it is too cold for them to survive, and pear bogs are too acidic.
How life began...
The horse
One of the few animals for which we have a fairly complete evolutionary record is the horse. All the main stages of the evolution of the horse have been preserved in fossil form.
Over 60 million years, the horse evolved from a dog-sized creature that lived in rainforests into an animal adapted to living on the plains and standing up to 2 metres high.
In the process its multi-toed feet, that were adapted for walking across the forest floor, evolved into single-toed hooves more suited for running over open country.

Individuals that are poorly adapted to their environment are less likely to survive and reproduce than those that are well adapted. Similarly, it is possible that a species that is poorly adapted to its environment will not survive and will become extinct.
Here are some of the factors that can cause a species to become extinct:
• New diseases
• New predators
• New, more successful competitors
• Changes to the environment over geological time - such as a change in climate
• A single catastrophic event - such as a massive volcanic eruption or a collision between an asteroid and the Earth
A species may also become extinct through speciation.The fossil record shows that many species have become extinct since life on Earth began. Extinction is still happening and a lot of it occurs because of human activities. We compete with other living things for space, food and water, and we are very successful predators.

Extinction

Extinction

Environmental changes
New predators
New diseases
Cannot compete with new species
Natural event
New species developed
Genetic variation - where each population has a wide range of alleles that control their characteristics
Natural selection - where the alleles which help an organism to survive are selected in each population
Speciation - where the populations become so different that successful interbreeding cannot happen anymore

Speciation
Physical barrier
Genetic variation
New populations adapt
New species develop
(cannot breed).
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